Definition:

Stage I is divided into stages IA, IB, and IC. In stage IA, the tumor is 5 millimeters or smaller and has not spread to the connective tissue of the eyelid or to the edge of the eyelid where the lashes are. In stage IB, the tumor is larger than 5 millimeters but not larger than 10 millimeters or has spread to the connective tissue of the eyelid or to the edge of the eyelid where the lashes are. In stage IC, the tumor is larger than 10 millimeters but not larger than 20 millimeters or has spread through the full thickness of the eyelid.